1. Field of the Invention
The present invention relates to a device for use in applying a liquid material consisting of a solder paste, a glue or another viscous liquid or liquid dispersion in discrete small quantities to selected points on a substrate, for instance an electric circuit board.
More particularly, the invention relates to such a device of the kind comprising a supply of said material, an outlet, connected to said supply by means of a conveying conduit, and means for intermittently forcedly discharging the material in successive small quantities through the outlet and applying each such quantity to a selected point on a substrate, placed in front of the outlet and movable in relation thereto.
2. Description of Related Art
Devices of the above kind are previously known which, similar to the device according to the invention, are primarily intended to be used for applying a solder paste or an electrically conductive glue on electric circuit boards before placing components intended to be surface mounted thereon, but which, similar to the device according to the invention, may be used also for applying other viscous liquids or liquid dispersions on any suitable kind of substrate.
A troublesome disadvantage of these known devices has been found to be that, both during the use of the devices as well as, and above all, during interruptions in their use, a sedimentation may easily occur in the conveying conduit extending between the supply and the outlet. This sedimentation may result in that the material discharged through the outlet will have quite another composition than intended. Moreover, the sedimentation in the conveying conduit may also cause heavy cloggings in said conduit, especially in the case of extended breaks in the use of the devices.